Hydrological patterns determine water depth, flow intensity, duration, and frequency of flooding, as well as low flow periods. Water levels in streams are not considered stable, but fluctuate seasonally. Hydrologic conditions primarily affect abiotic factors such as habitat structure, temperature and water chemistry, which in turn determine the biotic components (species composition, species richness, primary productivity) of the stream ecosystem. In PEI National Park, stream discharge (m3/sec) is predicted in four streams within PEI National Park using Onset HOBO U20 water level loggers and rating curves generated in four small 1 – 3rd order streams. Five informative parameters pertaining to fundamental hydrological characteristics are measured : mean daily water level, magnitude of annual min/max difference, Julian date of annual minimum water level, Julian date of annual maximum water level, and Richards-Baker Index (RBI). Standardized daily fluctuations are calculated annually (based on May 1 – April 30 water year) for each site and summarized into a stream flow index.